///////////////////////////////////////////////////////////////////////////////
// For information as to what this class does, see the Javadoc, below.       //
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// Scheines, Joseph Ramsey, and Clark Glymour.                               //
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// it under the terms of the GNU General Public License as published by      //
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package edu.cmu.tetrad.search.utils;

import edu.cmu.tetrad.data.DataSet;
import edu.cmu.tetrad.graph.Node;

/**
 * Gives an implemented  that is implemented by classes that evaluate scalar valued kernels
 *
 * @author Robert Tillman
 * @version $Id: $Id
 */
public interface Kernel {

    /**
     * Evaluates the kernel at two points in the input space
     *
     * @param i a double
     * @param j a double
     * @return a double
     */
    double eval(double i, double j);

    /**
     * Sets bandwidth from data using default method
     *
     * @param dataset a {@link edu.cmu.tetrad.data.DataSet} object
     * @param node    a {@link edu.cmu.tetrad.graph.Node} object
     */
    void setDefaultBw(DataSet dataset, Node node);

    /**
     * Gets kernel bandwidth
     *
     * @return a double
     */
    double getBandwidth();

}



